Safety-catch



L M Du .n S W e e h S 2 N A T S N U D J (No Model SAFETY CATCH-- Patented-Sept. 6, 1887.

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(No Model.) 2 Sheets-Sheet 2. J. DUNSTAN.

SAFETY CATCH.

Patentd Sept. 6

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UNITED STATES PATENT @rrrcn.

JAMES DUNSTAN, OF CENTRAL MINE, MICHIGAN.

SAFETY-CATCH.

SPECIFICATION forming part of Letters Patent No. 369,399, dated Sept-e her 6, 1887.

A Application died June 0. 1887. Serial No. 240,337, (ll'omodch) To (Z-ZZ whom it may concern:

Be itknown that 1, JAMES DUNSTAN,Of Central Mine, in the county of Keweenaw and State of Michigan, have invented certain new and useful Improvements in Safety-Catches, of which the following is a specification.

My invention relates to safety-catches or looking devices for use upon cars, elevator platforms, cages, &c.; and it consists in a novel construction and arrangement of eccentric gripping-dogs to engage upon opposite sides of a supporting or guiding rail and hold the car-platform or other vehicle against sudden descent in case of breakage of the draft or hoisting cable.

The invention isapplicable to any and all conveyances moving vertically or at an upward inclination, and liable in the event of breakage or disconnection of the draft rope or cable to descend with dangerous rapidity.

In the annexed drawings, Figure l represents the truck of a railway-car provided with my improved safety attachment; Fig. 2, an elevator-car similarly provided. Figs. 3 to 5, inclusive, are details.

Various safety devices have heretofore been invented and applied to cars, elevators, 870., and in some cases eccentric lockingdogs have been arranged in pairs to grip or bind upon opposite faces of a supporting or guiding rail in a manner analogous to those of my attachment. As heretofore employed, however, such devices have generally been so con structed or connected that each pair of jaws has been dependent in action upon the other pair, so that if from any cause one pair of jaws failed to act, the'other pair has been prevented from acting. This is a serious defect in construction, for the reason that in the event of the rail being provided with a fishplate, or other projection of any kind, which might interfere with or preclude the action of the gripping-jaws at a given point on one rail or guide, the jaws at the opposite side, which are designed to engage with the other rail, are prevented from acting, and thus the value and efficacy of the safety attachment is destroyed.

By my invention each pair of jaws is caused to act independently of the other, so that in case of obstruction on either rail or guide the jaws may freely grasp and bind upon the other, and thus the device be caused to act with certainty under all circumstances likely to arise.

Referringagain to the drawings, A indicates a car or vehicle,that in Fig. 1 being dcsignedfor ordinary railway tracks and that in Fig. 2 being a cage or platform for elevators; and B are the rails or guides upon or between which the vehicle moves; 0 G and D D, the dogs or gripping-jaws, arranged in pairs, one pair at each side of the vehicle, said jaws or dogs con sisting each of an eccentric or cam-shaped block having its outer face serrated or provided with teeth to engage with the sides of the rails or guides B. These teeth will be made, preferably, of the form shown in Fig. 5that is to say, they will present in side elevation the form of saw or ratchet teeth, and will be rounded from side to side, or in the direction of the axis of rotation, this rounding being designed to enable the dogs to engage with the rails or guides,whcther they be flatfaced or curved, and also to enable them to embed themselves more readily in the metal of the rails or guides than they could do if presenting a straight face the full width of the bearingface on the dogs.

Each dog or jaw C is carried by a shaft or arbor, E, provided with sector-gears F and G, which intermesh and cause the dogs to move toward or from each other simultaneously and equally when the arbors are rotated. The sector-gears G are each formed with a lever or extension, G, which extension is in turn connected with rods H. The forward ends of the rods H are connected by chains I I, or otherwise, to a ring or clevis, J, to which the draft rope, chain, or cable is attached. Another chain, K, extends from said clevis or ring to and is connected with the frame or draw-bar of the car, elevator, or other vehicle.

Each bar or rod H is pressed back by a spring, L, in the form of a coil or helix, encircling the rod and bearing at one end against a shoulder on the rod and at the other end against a fixed part of the frame of the vehicle. Said springs acting upon the rods or bars, each independently, tend to force said rods backward relatively to the direct-ion of travel of the vehicle,and thus to rotate the arbors E, through the action of the sector-gears, in such manner as to throw the dogs inward toward each other and to cause them to bind upon ICC the sides of the rail or guide which passes between them, as shown in Figs. 1 and 2. When, however, power is applied to the draft rope or cable, it draws said rods forward against the resistance of the springs, which are thus compressed and held in a state of compression,

such forward movement of the rods rotating the arbors E in a direction opposite to that occasioned by the compression of the springs, or in a direction to throw the dogs apart from each other and out of contact with the rails or guides. This forward movement of the rods and consequent separation of the dogs is limited by the chain K, which is made long enough to permit the necessary forward movement of the rods, but which, by the time such movement is completed, is drawn taut and receives ghe 1weight or resistance of the vehicle and its oac So long as the draft-rope is under strain the rods will remain in their forward position and the springs in a state of compression; but in the event of sudden slackening or breaking of the draft rope or cable the draft-rods will be thereby released and the springs acting upon them will force them instantly backward, thereby acting upon the extensions of the sector-gears, rotating the arbors E, and throwing the dogs into engagement with the rails or guides. Owingto the eccentricity of these dogs they will be forced inward with great pressure against the rails or guides by the weight of the vehicle and its load, and caused to hug the same so tightly as to preclude the downward or backward movement of the vehicle, as will be readily seen, and in the event of either pair of jaws being prevented, by fish plates or other projections upon the rail or guide, from properly swinging inward and engaging effectually with the rail, the jaws at the other side of the vehicle being wholly independent of and disconnected from the first pair, will still act promptly and efficiently, it being the custom in laying such rails or applying the guides to alternate the joints at opposite sides of the track or runway, and there being, conse quently, practically no danger of meeting with such obstructions at both sides simultaneously.

The precise arrangement or manner of mounting the toothed sectors, or of connecting their levers or extensions with the operatingrods, I do not deem important, and in fact it is necessary to vary the same somewhatin order to apply the devices both to cars and to elevators and like conveyances.

As shown in Fig. 1, where the invention is represented as applied to a car, the lovers or extensions G are shown perforated or slotted for the passage through them of the rods or bars H, which latter are provided with through-pins a, to bear against opposite sides or faces of the extensions G, it being obvious, however, that any form of shoulder or abutment may be adopted in lieu of the pins, to bear against the extensions.

In Fig. 2 an analogous arrangement is adopted; but for convenience of application, and in order to avoid the presence of the rods at the middle of the car, which would in many cases be inconvenient,each lever G is connected by a rod, H, with a second lever, H, to which the chains are attached, the levers H extending across the top of the car-frame from the side beams or standards to a point at or near the middle in line with the draft rope or cable.

It will be observed that under the construction and arrangement above described, and shown in the drawings, either pair of dogs may act entirely independent of the other, though under ordinary circumstances both pairs will act; and it will also be seen that both in the case of cars and of hoists of all kinds the two dogs of each pair bear with equal force upon opposite sides of the rail or guide, so that the two forces exactly equalize each other, and there is no spreading action exerted to force the rails or guides from each other, as would be the case were the pressure applied to either side alone. It will also be seen that by reason of the toothed gearing or connection between the jaws of each pair the r action is rendered positive, certain, and umform.

' It is obvious that good results may be secured, especially in the case of elevators-and other vehicles having a vertical or substantially vertical movement, without the aid of the springs, the weight of the rods and the levers being in such case suflicient to insure the prompt engagement of the dogs with the rails; but I prefer in all cases to employ the springs, because of the greater promptness and certainty of action thereby secured.

Having thus described my invention, what I claim is- 1. In combination with a car or other vehicle, two independent pairs of gripping jaws or dogs, the jaws of each pair being arranged, substantially as shown and described, to bear against opposite faces of the rail or guide over which the vehicle moves.

2. In combination with a car or other vehicle, two pairs of gripping jaws or dogs, each pair independently connected with the draft rope or cable, whereby each pair is adapted to independently engage with the supporting or guiding rail upon or over which the vehicle moves in the event of breakage or sudden slackening of the draft rope or cable.

3. In combination with a car or other vehi cle and with supporting or guiding rails therefor, two pairs of arbors, E, toothed gearing connecting the arbors of each pair, eccentric dogs carried one by each of said arbors, levers projecting from said arbors,and longitudinallymovable rods connecting said levers with the draft rope or cable, all substantially as shown, whereby the rods are permitted to move backward upon sudden slackening or breakage of the draft rope or cable and in moving back to actuate the jaws and throw them into engagemeat with opposite faces of the supporting or guiding rails.

41:. In combination with supporting or guiding rails 13, a car or vehicle provided with an bors E, gripping-dogs G, secured to said arbors and arranged to bear against opposite sides of said rails, toothed gearing connecting the arbors of each pair, levers G, extending radially from one arbor of each pair, longitudinallyinovable rods connected with said levers, springs bearing against said rods and tending to force the same backward relatively to the direction of movement of the vehicle, and a draft rope or cable independently connected with each of said rods, substantially as set forth.

5. The hcreindeseribed safety attachment for cars, elevators, 850., consisting of arbors E, dogs (3, carried by said arbors, toothed gearing F G, connecting said arbors E, levers G, extending from the arbors E, and a draft rope or cable connected independently with each of said levers.

6. In combination with guiding or supporting rails, a car or vehicle provided with arbors E, dogs 0, secured upon said arbors, gearing F G, connecting the arbors of each pair, levers G, extending from the arbors E, longitudinally-movable rods H, connected with said levers, springs L, acting upon said rods, and a draft rope or cable independently connected with each of said rods and with the car or ve hicle, substantially as shown and described, whereby the rods are drawn and held forward against the pressure of the springs when the draft rope or cable is under tension, but are released and permitted to move back when said tension is relieved, substantially as set forth.

In witness whereof I hereunto set my hand in the presence of two witnesses.

JAMES DUNSTAN.

Witnesses: 7

CHARLES D. Hnncnnrrn, THOMAS B. DUNSIAN. 

